JPS6212801Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a gas turbine blade, and particularly to improvements in its cap and its mounting structure.

[Technical background of the invention and its problems]

Gas turbine blades operate in very high temperature atmospheres, so the side walls of the blades must be cooled.For this reason, a cavity for cooling air is formed inside the blade, and a compressor is installed in this cavity. A portion of the compressed air that is led from the diffuser to the diffuser is introduced to cool the wing sidewalls. In addition, in order to increase the cooling effect, irregularities are formed on the side walls of the cavity,
They also have ribs.

As mentioned above, since the airfoils have complex configurations, wings are generally made by precision casting.
A core made of ceramics or the like is used to form the void. To facilitate this manufacturing process, it is common to leave the cavity open at the end and allow the core to protrude outwardly from the cavity's opening for handling and positioning during manufacturing. After manufacturing, the leading end of the cavity is closed with a cap to prevent cooling air from being discharged from the leading end of the cavity into the turbine driving gas. By the way, the cap is subjected to a very large centrifugal force due to the high speed rotation of the blades.

A conventional type of such a gas turbine blade is shown in FIG.

In FIG. 1, a cooling air space 2 is formed in a blade 1 of a gas turbine, and step portions 4, 4 are formed on both side walls 3a, 3b of this space 2. , 4 is bridged with a flat cap 5. This cap 5 is fixed to both side walls 3a and 3b with a suitable brazing alloy 6. However, fixing with such a brazing alloy 6 does not have sufficient strength against strong centrifugal force, so a pin 9 is inserted into a hole 8 drilled in the side wall 7b of the wing 1 to prevent the cap 5 from coming off. In addition, this pin 9 was fixed with a brazing alloy 6.

According to such a configuration, the cap 5 has sufficient strength against centrifugal force, but the pin 9 and the brazing alloy 6 protrude outside the side wall 7b, which may disturb the configuration of the blade row. .

The conventional one shown in FIGS. 2 and 3 is different from the one shown in FIG.
This shows a conventional technique in which the outside of the cap 7b is flat, and above the cap 12 both side walls 7a,
7b is bent inward to prevent the cap 12 from coming off.

According to such a configuration, unlike the configuration described above, the configuration of the blade row is not disturbed, but since the tip shape of the blade 11 is different from the normal shape, there is a risk that the turbine efficiency will be reduced.

[Purpose of invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the conventional blades and to provide a gas turbine blade to which a cap can be securely attached without destroying the airfoil shape of the blade tip.

[Summary of the idea]

According to the present invention, the above-mentioned object is achieved by constructing the cap from a flexible material and having a cross section of approximately U.
This is achieved by forming the cap into a letter shape, forming grooves on opposite side walls of the cavity, and fitting and fixing both ends of the cap into both grooves.

[Example of idea]

The present invention will be explained below with reference to embodiments shown in the drawings.

4 and 5, near the tips of both side walls 3a and 3b of the cooling air space 2 of the blade 13,
Protrusions 14a and 14b extending horizontally are formed at the same vertical position, and each protrusion 14
Horizontal long grooves 15a, 15b are formed in a, 14b. On the other hand, the cap 16 for closing the space 2 is made of a flexible material and has a substantially U-shaped cross section and a longitudinal shape corresponding to the shape of the airfoil. 1
Horizontal protrusion 17 that can be fitted relatively tightly into 5b
a and 17b are provided in a protruding manner. Then, both protrusions 17a and 17b of the cap 16 are inserted into the long grooves 1.
Cap 1 when inserted into 5a and 15b
6 has dimensions such that no or only a slight amount of deflection remains. Furthermore, Figures 6 to 8
As shown in the figure, the bottom of the cap 16 includes:
A large number of small diameter holes 18a, 18a, 18b, 18b extending substantially tangentially to the arc of the cap 16.
... are bored in a staggered manner in the longitudinal direction of the cap 16.

Next, the operation of the embodiment described above will be explained.

The protrusions 17a, 17b of the cap 16 are inserted into the long grooves 15a, 1 in the side walls 3a, 3b of the cooling air space 2.
5b, one protrusion 17a is inserted into the long groove 15a, and the cap 16 is inserted into the fifth
The other protrusion 17b is bent as shown by the broken line in the figure.
What is necessary is just to fit into the other long groove 15b. Thereafter, both protrusions 17a and 17b of the cap 16 are fixed to the protrusions 14a and 14b of the side walls 3a and 3b of the cavity 2 with brazing alloy 6, and both ends of the cap 16 are fixed to the blades 13 with brazing alloy 6.
It is fixed to the reinforcing ribs 19, 19, and heated in a furnace.

When the blades 13 of the gas turbine of this embodiment manufactured as described above rotate at high speed, the blades 13 are deformed by centrifugal force, torsional force, and the like. However, since this deformation of the blade is absorbed by the deflection of the cap 16, stress due to the deformation is not generated in the fixed portion between the blade 13 and the cap 16. Further, the cap expands due to the centrifugal force acting on the cap 16, and both ends 17a and 17b of the cap open into the long groove 15.
Since the cap 16 is pushed into the caps 15a and 15b, the cap 16 is fixed more firmly as the centrifugal force increases. Further, since the small diameter holes 18a and 18b are arranged in a staggered manner, the cooling air ejected from each of the small diameter holes 18a and 18b of the cap 16 flows along the cap 16 without interfering with each other, and flows along the side walls 7a of the blade 13,
7b is well cooled.

In the above-described embodiment, the blade 13 has only one cavity 2. However, if a plurality of cavities are formed by the auxiliary ribs, it is only necessary to attach a cap corresponding to each cavity.

[Effect of idea]

As explained above, the gas turbine blade according to the present invention has at least one cavity for cooling air formed inside, and this cavity is closed by a cap disposed on the tip side. The cap is made of a flexible material, is formed into a substantially U-shaped cross section, and grooves are formed in opposite side walls of the cavity, and both ends of the cap are fitted into the grooves and fixed. This prevents stress caused by the deformation of the wing from occurring at the fixed part between the wing and the cap, and as the centrifugal force increases, the cap can be fixed more firmly, and the shape of the airfoil at the tip of the wing can be prevented. This has the excellent effect of allowing the cap to be firmly attached without any problems.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of the main parts of a conventional gas turbine blade, FIG. 2 is a plan view of another conventional gas turbine blade, and FIG. 3 is a cross-sectional view taken along the line - in FIG. 2. FIG. 4 is a plan view showing an embodiment of a gas turbine blade according to the present invention, and FIG.
6 is a plan view showing the details of the cap in FIG. 5, FIG. 7 is a sectional view taken along the - line in FIG. 6, and FIG. 8 is a sectional view taken along the - line in FIG. 4. be. 1, 11, 13...Gas turbine blades, 2...
Cooling air space, 5, 12, 16...cap,
15a, 15b...Long groove, 17a, 17b...Protrusion.

Claims (1)

[Scope of utility model registration request] A gas turbine blade having at least one cavity for cooling air formed therein, the cavity being closed by a cap disposed on the tip side, wherein the cap is made of a flexible material and has a substantially U-shaped cross section. A blade for a gas turbine, characterized in that grooves are formed in opposing side walls of the cavity, and both ends of the cap are fitted and fixed into the grooves.